If the solution set of (x^{2} + kx – 5 = 0) is (-1, 5), find the value of k.
-
A.
-6 -
B.
-4 -
C.
4 -
D.
5
Correct Answer: Option B
Explanation
Given x = (-1, 5) for the equation (x^{2} + kx – 5 = 0)
(x = -1 implies x + 1 = 0); (x = 5 implies x – 5 = 0)
((x + 1)(x – 5) = 0), expanding,
(x^{2} – 5x + x – 5 = 0 therefore x^{2} – 4x – 5 = 0)
(therefore) k = -4.